Scotland hugely overvalued potential of tidal energy

Estimates of energy yields from tidal turbines in the Pentland Firth could be up to 1000% off

A study, carried out by the University of Oxford, has revealed that tidal turbines located between Orkney and mainland Scotland can produce only a fraction of what was previously thought.

Dr Thomas Adcock from the University of Oxford’s department of engineering science, set maximum output levels at 1.9GW, a far cry from the 10GW previously mentioned.

Practical limitations

Adcock says that part of the reason for the overvaluation is down to the practical limitations of installing tidal turbines, which previous reports failed to take into account.

Although 1.9GW of energy would be enough to cater for almost half of Scotland’s current electricity needs, the actual level that is likely to be generated is 1GW. This represent just a tenth of the 10GW that was initially predicted.

The news comes as a blow to the Scottish Government, which had harboured ambitions of exporting surplus energy in a bid to boost economic growth and illustrate its case for independence.

Revised ambitions

The administration has previously claimed that Scotland has 25% of Europe’s tidal energy potential, which equates to around 14GW. However, Adcock says it is naive not to factor in the extreme difficulty of extracting every drop of energy and the substantial central planning that would be required.

“Pentland Firth promises to be one of the best sites in the world for tidal power. Our study provides the first robust data about how much energy it would be feasible to extract,” the expert says in the report.

During the study, researchers used mathematical models to establish how different rows of turbines would potentially interact and calculated the best way to arrange them so that they did not cancel each other out.

Dr Adcock went on to say that, in order to be efficient, any scheme would have to be “joined up” so that individual tidal turbines did not cannibalise each other, while provisions would need to be made to store the greater energy produced by spring tides, which could then be fed back in at neap tides.

“Building handfuls of tidal turbines in ‘plots’ of ocean leased out to individual developers is not going to extract the maximum energy from Pentland Firth. To make the most of this unique site the placement of turbines would need to be carefully planned,” he added.

Remains valid energy generation project

After acknowledging that the Scottish Government has “many reasons” to promote its renewable energy resources and secure the investment to harness it, Adcock poined out that the estimates his report gives for the Pentland Firth are far greater than the realistic potential.

“There’s a huge amount of tidal power there but it’s certainly not the case that Scotland will be able to export its tidal energy, which has been one of the arguments for Scottish independence,” he concluded.

The Scottish Government is yet to issue an official response to the report, which was commissioned and supported by the Energy Technologies Institute.

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